Novel dyeing composition for dyeing keratinous fibres comprising a particular dicationic diazo dye

ABSTRACT

The invention concerns a novel dyeing composition for dyeing keratinous fibres, in particular human hair, comprising a dicationic diazo dye of formula (I): W1—W2—N═N—W3—L—W4—N═N—W5—W6, as well as the dyeing method using said composition and the novel compounds of formula (I).

[0001] A subject matter of the invention is a novel dyeing compositionfor the dyeing of keratinous fibers, in particular of human hair,comprising a specific dicationic diazo dye and the process for dyeingkeratinous fibers employing such a composition. Another subject matterof the invention is novel dicationic diazo dyes.

[0002] It is known to dye keratinous fibers and in particular human hairwith dyeing compositions comprising oxidation dye precursors, generallyknown as oxidation bases, such as ortho- or para-phenylenediamines,ortho- or para-aminophenols and heterocyclic compounds. These oxidationbases are colorless or weakly colored compounds which, in combinationwith oxidizing substances, give rise to colored compounds by anoxidative coupling process.

[0003] It is also known that the hues obtained with these oxidationbases can be varied by combining them with couplers or coloringmodifiers, the latter being chosen in particular from aromaticmeta-diamines, meta-aminophenols meta-diphenols and certain heterocycliccompounds, such as indole compounds.

[0004] The variety of the molecules employed as oxidation bases andcouplers makes it possible to obtain a rich palette of colors.

[0005] This oxidation dyeing process consists in applying, to thekeratinous fibers, oxidation bases or a mixture of oxidation bases andof couplers with an oxidizing agent, for example aqueous hydrogenperoxide solution, in leaving to stand and in then rinsing the fibers.The colorations which result therefrom are permanent and powerful, andwithstand external agents, in particular light, bad weather, washing,perspiration and rubbing. Generally applied at basic pH, they make itpossible to obtain dyeing and simultaneously lightening of the fiber,which is reflected in practice by the possibility of obtaining a finalcoloration which is lighter than the original color. In addition,lightening the fiber has the advantageous effect of producing a unifiedcolor in the case of gray hair and, in the case of naturally pigmentedhair, of making the color emerge, that is to say of rendering it morevisible.

[0006] It is also known to dye human keratinous fibers by direct dyeing.The process conventionally used in direct dyeing consists in applying,to the keratinous fibers, direct dyes, which are colored and coloringmolecules having an affinity for the fibers, in leaving to stand and inthen rinsing the fibers.

[0007] It is known, for example, to use nitrobenzene, anthraquinone ornitropyridine direct dyes, azo, xanthene, acridine or azine dyes ortriarylmethane dyes.

[0008] The colorations which result therefrom are particularly chromaticcolorations which, however, are temporary or semipermanent because thenature of the interactions which bind the direct dyes to the keratinousfiber and their desorption from the surface and/or from the core of thefiber are responsible for their low dyeing power and for their poorresistance to washing or to perspiration. In addition, these direct dyesare generally sensitive to light, because of the low resistance of thechromophore with regard to photochemical attacks, and result over timein fading of the coloring of the hair. In addition, their sensitivity tolight is dependent on their distribution, uniform or nonuniform, in thekeratinous fiber.

[0009] It is known to use direct dyes in combination with oxidizingagents. However, direct dyes are generally sensitive to the action ofoxidizing agents, such as aqueous hydrogen peroxide solution, andreducing agents, such as sodium bisulfite, which generally renders themdifficult to use in compositions for lightening direct dyeing based onaqueous hydrogen peroxide solution and based on a basifying agent or inoxidation dyeing compositions in combination with oxidation dyeprecursors or couplers.

[0010] For example, provision has been made, in Patent Applications FR-1584 965 and JP-062 711 435, to dye the hair with dyeing compositionsbased on direct nitro dyes and/or on disperse azo dyes and on aqueousammoniacal hydrogen peroxide solution by applying, to the hair, amixture of said dyes and of said oxidizing agent prepared immediatelybefore use. However, the colorations obtained prove to be insufficientlypersistent and disappear on shampooing, allowing the lightening of thehair fiber to become apparent. Such a coloration becomes unattractive onchanging over time.

[0011] Provision has also been made, in Patent Applications JP-53 95693and JP 55 022638, to dye the hair with compositions based on cationicdirect dyes of oxazine type and on aqueous ammoniacal hydrogen peroxidesolution by applying, to the hair, in a first stage, aqueous ammoniacalhydrogen peroxide solution and then, in a second stage, a compositionbased on the direct oxazine dye. This coloration is not satisfactorybecause of the fact that it requires a process rendered excessively slowby the leave-in times of the two successive stages. Furthermore, if amixture prepared at the time of use of the direct oxazine dye withaqueous ammoniacal hydrogen peroxide solution is applied to the hair, nocoloration is produced or, at least, a coloration of the hair fiber isobtained which is virtually nonexistent.

[0012] More recently, Patent Application FR 2 741 798 has discloseddyeing compositions comprising direct azo or azomethine dyes comprisingat least one quaternized nitrogen atom, said compositions having to bemixed at the time of use at basic pH with an oxidizing composition.These compositions make it possible to obtain colorations withhomogeneous, persistent and bright highlights. However, they do not makeit possible to dye keratinous fibers with as much power as withoxidation dyeing compositions.

[0013] There thus exists a real need to try to find chromatic directdyes which make it possible to dye keratinous fibers as powerfully asoxidation dyes, which are as stable as them toward light and are alsoresistant to bad weather, washing and perspiration, and which, inaddition, are sufficiently stable in the presence of oxidizing andreducing agents to be able to simultaneously obtain lightening of thefiber, either by use of lightening direct compositions comprising themor by the use of oxidation dyeing compositions comprising them. Therealso exists a real need to try to find direct dyes which make itpossible to dye keratinous fibers in order to obtain a very broad rangeof colors, in particular highly chromatic colors, without forgetting the“basic” shades, such as the blacks and the browns.

[0014] These aims are achieved with the present invention, a subjectmatter of which is a composition for dyeing keratinous fibers, and inparticular human keratinous fibers such as the hair, comprising at leastone dicationic diazo dye of the following formula (I):

W₁—W₂—N═N—W₃—L—W₄—N═N—W₅—W₆  Formula (I)

[0015] in which

[0016] W₁ and W₆ represent, independently of one another, a radicalNR₁R₂

[0017] W₂ and W₅ represent, independently of one another, a carbonaceousaromatic, pyridine or pyridazinyl group of formula (II)

[0018] W₃ and W₄ represent, independently of one another, aheteroaromatic radical represented by the following formulae (III) and(IV):

[0019] in which

[0020] X₁ represents a nitrogen atom or a radical CR₅,

[0021] X₂ represents a nitrogen atom or a radical CR₆,

[0022] Z₁ represents an oxygen or sulfur atom or a radical NR₈,

[0023] Z₂ represents a nitrogen atom or a radical CR₉,

[0024] Z₃ represents a nitrogen atom or a radical CR₁₂,

[0025] Z₄ represents a nitrogen atom or a radical CR₁₃,

[0026] N¹ of the 5-membered ring of formula (III) is connected to thegroup L and the bond a of the same 5-membered ring is connected to theazo group of formula (I),

[0027] the bond b of the 6-membered ring of formula (IV) is connected tothe azo group of formula (I) and N¹ of the 6-membered ring of formula(IV) is connected to the group L,

[0028] L, R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃represent, together or independently of one another, a linear orbranched C₁-C₁₆ hydrocarbonaceous chain, which can form one or more 3-to 6-membered carbonaceous rings, and which can be saturated orunsaturated, of which one or more carbon atoms of the carbonaceous chaincan be replaced by an oxygen, nitrogen or sulfur atom or by an SO₂group, and the carbon atoms of which can be, independently of oneanother, substituted by one or more halogen atoms; R₁, R₂, R₃, R₄, R₅,R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃ can represent hydrogen; L, R₁, R₂, R₃,R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃ not comprising a peroxidebond, or diazo or nitroso radicals, and L is a divalent radical,

[0029] R₈ represents a linear or branched C₁-C₈ alkyl radical optionallysubstituted by one or more radicals chosen from hydroxyl, C₁-C₂ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl orsulfonic radicals; an optionally substituted phenyl radical,

[0030] R₇ with R₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ can form a carbonaceousaromatic ring such as a phenyl,

[0031] R is a C₁-C₃ alkyl radical,

[0032] X is an organic or inorganic anion.

[0033] In the context of the present invention, the term “alkyl”, unlessotherwise stated, is understood to mean an alkyl radical comprising from1 to 10 carbon atoms, preferably from 1 to 6 carbon atoms, which may belinear or branched. The term alkoxy means alkyl-O—, the term alkylhaving the above meaning.

[0034] According to the invention, when it is indicated that one or moreof the carbon atoms of the hydrocarbonaceous chain defined for theradicals L, R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃ can bereplaced by an oxygen, nitrogen or sulfur atom or by an SO₂ group,and/or that these hydrocarbonaceous chains are unsaturated, this meansthat it is possible, by way of example, to carry out the followingconversions:

can become

can become

can become

can become

can become

[0035] In particular, the expression “branched hydrocarbonaceous chain”is understood to mean a chain which can form one or more 3- to6-membered carbonaceous rings. The expression unsaturatedhydrocarbonaceous chain is understood to mean a chain which can compriseone or more double bonds and/or one or more triple bonds, it beingpossible for this hydrocarbonaceous chain to lead to aromatic groups.

[0036] X is an organic or inorganic anion, for example, chosen from ahalide such as chloride, bromide, fluoride, iodide; a hydroxide; asulfate; a hydrogen sulfate; a (C₁-C₆)alkyl sulfate such as for examplea methyl sulfate or an ethyl sulfate; an acetate; a tartrate; anoxalate; a (C₁-C₆)alkyl sulfonate such as methyl sulfonate; an arylsulfonate which is unsubstituted or substituted by a C₁-C₄ alkyl radicalsuch as for example a 4-toluoyl sulfonate.

[0037] R₁ and R₂ represent, preferably and independently of one another,a hydrogen atom; a linear or branched C₁-C₆ alkyl radical, optionallysubstituted by one or more radicals chosen from hydroxyl, C₁-C₂ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl orsulfonic radicals; a phenyl radical optionally substituted by one ormore radicals chosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl or sulfonicradicals or a halogen atom such as chlorine, fluorine or bromine; aC₁-C₄ alkylsulfonyl radical; an arylsulfonyl radical; a radical chosenfrom pyrazolyl, imidazolyl, thiazolyl, oxazolyl, thiadiazolyl,triazolyl, pyrrolyl, pyridyl, pyrimidinyl, triazinyl, pyrazinyl andpyridazinyl radicals.

[0038] R₁ and R₂ together can form a 5-, 6-, 7- or 8-memberedheterocyclic radical optionally substituted by one or more hydroxyl oramino radicals; a group —NR₁₄R₁₅ in which R₁₄ and R₁₅ represent,independently of one another, a hydrogen atom, a linear or branchedC₁-C₄ alkyl radical substituted by one or more radicals chosen from ahalogen atom, a hydroxyl, C₁-C₂ alkoxy, amino or C₁-C₂ amino(di)alkyl,or (poly)hydroxyalkylamino radical; a sulfonylamino radical; a carboxylradical; a carboxamido radical; a C₁-C₆ alkyl radical optionallysubstituted by one or more hydroxyl or amino radicals; a group —NR₁₄R₁₅.

[0039] The asymmetric carbons of said 5-, 6-, 7- or 8-memberedheterocycles may be of the (R) and/or (S) configuration.

[0040] R₁ and R₂ together can also form a 5- or 6-memberedheteroaromatic radical such as pyrazole, imidazole, pyrrole, triazole,pyridazine, pyrimidine.

[0041] R₁ and R₂ represent, preferably and independently of one another,a hydrogen atom; a linear or branched C₁-C₃ alkyl radical optionallysubstituted by one or more radicals chosen from the hydroxyl, C₁-C₂alkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl or sulfonic radicals; aphenyl radical optionally substituted by one or more radicals chosenfrom amino, C₁-C₂ (di)alkylamino or (poly)hydroxyalkylamino radicals; R₁and R₂ together form a 5- or 6-membered heterocycle optionallysubstituted by one or more radicals chosen from methyl, hydroxyl, aminoor (di)methylamino radicals, a sulfonylamino radical, a C₂-C₄(poly)hydroxyalkylamino radical, a carboxyl radical or a carboxamidoradical.

[0042] According to a particularly preferred embodiment, R₁ and R₂represent, preferably and independently of one another, a hydrogen atom;a linear or branched C₁-C₃ alkyl radical, such as methyl, ethyl,2-hydroxyethyl, 2-aminoethyl; 1-carboxymethyl, 2-carboxyethyl,2-sulfonylethyl, 2-methoxyethyl; a phenyl radical optionally substitutedby one or more radicals chosen from amino, C₁-C₂ (di)alkylamino or(poly)hydroxyalkylamino radicals; R₁ and R₂ together form a 5- or6-membered heterocycle pyrrolidine or piperidine optionally substitutedby one or more methyl, hydroxyl, amino, (di)methylamino, carboxyl orcarboxamido radicals.

[0043] R₁ and R₂ represent, preferably and independently of one another,a hydrogen atom; a methyl or 2-hydroxyethyl radical; a phenyl radicaloptionally substituted by an amino, (di)methylamino or(di)(2-hydroxyethyl)amino radical; R₁ and R₂ together form a 5- or6-membered heterocycle such as pyrrolidine, 3-hydroxypyrrolidine,piperidine or 3-hydroxypiperidine.

[0044] R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂ and R₁₃ represent, preferably andindependently of one another, a hydrogen atom; a linear or branchedC₁-C₄ alkyl radical optionally substituted by one or more radicalschosen from the hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy,amino, C₁-C₂ (di)alkylamino, carboxyl or sulfonic radicals; a phenylradical optionally substituted by one or more radicals chosen fromhydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl or sulfonic radicals or a halogen atom such aschlorine, fluorine or bromine; a carboxyl radical; a sulfonylaminoradical; a sulfonic radical; a C₁-C₂ alkoxy radical; a C₂-C₄(poly)hydroxyalkoxy radical; an amino radical; a C₁-C₂ (di)alkylaminoradical; a C₂-C₄ (poly)hydroxyalkylamino radical.

[0045] More preferably, R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂ and R₁₃ representa hydrogen atom, a C₁-C₄ alkyl radical optionally substituted by one ormore radicals chosen from the hydroxyl, amino or C₁-C₂ (di)alkylaminoradicals; a carboxyl radical; a C₁-C₂ alkoxy radical; an amino radical;a C₁-C₂ (di)alkylamino radical; a C₂-C₄ (poly)hydroxyalkylamino radical.

[0046] According to a particularly preferred embodiment, R₃, R₄, R₅, R₆,R₁₀, R₁₁, R₁₂ and R₁₃ represent a hydrogen atom, a methyl, phenyl or2-hydroxymethyl radical, a carboxyl, a methoxy, ethoxy or2-hydroxyethyloxy radical, an amino, methylamino, dimethylamino or2-hydroxyethylamino radical.

[0047] R₇ and R₉ represent, independently of one another, a hydrogenatom; a linear or branched C₁-C₄ alkyl radical, optionally substitutedby one or more radicals chosen from the hydroxyl, C₁-C₂ alkoxy, C₂-C₄(poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl or sulfonicradicals; an optionally substituted phenyl radical; a carboxyl radical;a sulfonylamino radical.

[0048] Among these substituents, R₇ and R₉ preferably represent ahydrogen atom, a phenyl radical, a C₁-C₄ alkyl radical optionallysubstituted by one or more radicals chosen from the hydroxyl, amino,C₁-C₂ (di)alkylamino and carboxyl radicals.

[0049] According to a particularly preferred embodiment, R₇ and R₉preferably represent a hydrogen atom, a methyl, phenyl or2-hydroxymethyl radical, or a carboxyl.

[0050] R₈ preferably represents a C₁-C₄ alkyl radical optionallysubstituted by one or more radicals chosen from hydroxyl, C₁-C₂ alkoxy,amino, C₁-C₂ (di)alkylamino, carboxyl or sulfonic radicals. According toa particularly preferred embodiment, R₈ preferably represents a methyl,ethyl, 2-hydroxyethyl, 1-carboxymethyl, 2-carboxyethyl or2-sulfonylethyl radical.

[0051] According to a particular embodiment, W1 and W6 are NR₁R₂ and R₁and R₂ are preferably chosen from hydrogen, an alkyl radical which canbe substituted by a hydroxyl or an amino.

[0052] According to another embodiment, W1 and W6 are OR and R ispreferably a methyl radical.

[0053] In formula (I), W2 and W5 are preferably carbonaceous aromaticradicals. Preferably, W2 and W5 represent a phenyl radical optionallysubstituted by an alkyl, alkoxy, amino, or mono- or di-substituted aminoradical. By way of example, W2 and W5 are phenyl radicals substituted bya methoxy radical, a methyl radical, an amino radical, a methylaminoradical or a dimethylamino radical.

[0054] W3 and W4 are preferably chosen from imidazolinium, triazoliumand pyridinium radicals.

[0055] According to a particularly preferred embodiment, W2 and W5 arephenylene radicals, W3 and W4 are imidazolinium radicals.

[0056] In formula (I), L is preferably a linear or branched C₁-C₈alkylene radical, optionally substituted by one or more radicals chosenfrom the hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂(di)alkylamino, carboxyl or sulfonic radicals; preferably a linear orbranched C₁-C₈ alkylene radical. According to a preferred embodiment, Lis a linear or branched C₁-C₈ alkylene radical, optionally substitutedby one or more radicals chosen from the hydroxyl, C₁-C₂ alkoxy, aminoand C₁-C₂ (di)alkylamino radicals.

[0057] The concentration of dicationic diazo dye of formula (I) can varybetween 0.001 and 5% by weight approximately relative to the totalweight of the dyeing composition, and preferably between approximately0.05 and 2%.

[0058] The composition of the invention can furthermore comprise anoxidizing agent. This oxidizing agent can be any oxidizing agentconventionally used for bleaching keratinous fibers. The oxidizing agentis preferably chosen from hydrogen peroxide, urea peroxide, alkali metalbromates, persalts such as perborates and persulfates. The use ofhydrogen peroxide is particularly preferred.

[0059] The composition according to the invention can furthermorecomprise an oxidation base. This oxidation base can be chosen from theoxidation bases conventionally used in oxidation dyeing, for examplepara-phenylenediamines, bisphenylalkylenediamines, para-aminophenols,ortho-aminophenols and heterocyclic bases.

[0060] Mention may more particularly be made, amongpara-phenylenediamines, by way of example, of para-phenylenediamine,para-tolylenediamine, 2-chloro-para-phenylenediamine,2,3-dimethyl-para-phenylenediamine, 2,6-dimethyl-para-phenylenediamine,2,6-diethyl-para-phenylenediamine, 2,5-dimethyl-para-phenylenediamine,N,N-dimethyl-para-phenylenediamine, N,N-diethyl-para-phenylenediamine,N,N-dipropyl-para-phenylenediamine, 4-amino-N,N-diethyl-3-methylaniline,N,N-bis(β-hydroxyethyl)-para-phenylenediamine,4-N,N-bis(β-hydroxyethyl)amino-2-methylaniline,4-N,N-bis(β-hydroxyethyl)amino-2-chloroaniline,2-(β-hydroxyethyl)-para-phenylenediamine,2-fluoro-para-phenylenediamine, 2-isopropyl-para-phenylenediamine,N-(β-hydroxypropyl)-para-phenylenediamine,2-hydroxymethyl-para-phenylenediamine,N,N-dimethyl-3-methyl-para-phenylenediamine, N,N-(ethyl,β-hydroxyethyl)-para-phenylenediamine,N-(β,γ-dihydroxypropyl)-para-phenylenediamine,N-(4′-aminophenyl)-para-phenylenediamine,N-phenyl-para-phenylenediamine,2-(β-hydroxyethyloxy)-para-phenylenediamine,2-(β-acetylaminoethyloxy)-para-phenylenediamine,N-(β-methoxyethyl)-para-phenylenediamine, 4-(aminophenyl)pyrrolidine,2-thienyl-para-phenylenediamine, 2-(β-hydroxyethylamino)-5-aminotoluene,and their addition salts with an acid.

[0061] Among the para-phenylenediamines mentioned above,para-phenylenediamine, para-tolylenediamine,2-isopropyl-para-phenylenediamine,2-(β-hydroxyethyl)-para-phenylenediamine,2-(β-hydroxyethyloxy)-para-phenylenediamine,2,6-dimethyl-para-phenylenediamine, 2,6-diethyl-para-phenylenediamine,2,3-dimethyl-para-phenylenediamine,N,N-bis(β-hydroxyethyl)-para-phenylenediamine,2-chloro-para-phenylenediamine,2-(β-acetylaminoethyloxy)-para-phenylenediamine, and their additionsalts with an acid, are particularly preferred.

[0062] Mention may be made, among bisphenylalkylene-diamines, by way ofexample, ofN,N′-bis(β-hydroxyethyl)-N,N′-bis(4′-aminophenyl)-1,3-diaminopropanol,N,N′-bis(β-hydroxyethyl)-N,N′-bis(4′-aminophenyl)ethylenediamine,N,N′-bis(4-aminophenyl)tetramethylenediamine,N,N′-bis(β-hydroxyethyl)-N,N′-bis(4-aminophenyl)tetramethylenediamine,N,N′-bis(4-methylaminophenyl)tetramethylenediamine,N,N′-bis(ethyl)-N,N′-bis(4′-amino-3′-methylphenyl)-ethylenediamine,1,8-bis(2,5-diaminophenoxy)-3,6-dioxaoctane, and their addition saltswith an acid.

[0063] Mention may be made, among para-aminophenols, by way of example,of para-aminophenol, 4-amino-3-methylphenol, 4-amino-3-fluorophenol,4-amino-3-(hydroxymethyl)phenol, 4-amino-2-methylphenol,4-amino-2-(hydroxymethyl)phenol, 4-amino-2-(methoxymethyl)phenol,4-amino-(2-aminomethyl)phenol,4-amino-2-[(β-hydroxy-ethyl)aminomethyl]phenol, 4-amino-2-fluorophenol,and their addition salts with an acid.

[0064] Mention may be made, among ortho-aminophenols, by way of example,of 2-aminophenol, 2-amino-5-methylphenol, 2-amino-6-methylphenol,5-acetamido-2-aminophenol, and their addition salts with an acid.

[0065] Mention may be made, among heterocyclic bases, by way of example,of pyridine derivatives, pyrimidine derivatives and pyrazolederivatives.

[0066] Mention may be made, among pyridine derivatives, of the compoundsdisclosed, for example, in Patents GB 1 026 978 and GB 1 153 196, suchas 2,5-diaminopyridine, 2-(4-methoxyphenyl)amino-3-aminopyridine,2,3-diamino-6-methoxypyridine,2-(β-methoxyethyl)amino-3-amino-6-methoxypyridine, 3,4-diaminopyridine,and their addition salts with an acid.

[0067] Mention may be made, among pyrimidine derivatives, of thecompounds disclosed, for example, in Patents DE 2 359 399, JP 88-169571, JP 05 163 124 or EP 0 770 375 or Patent Application WO 96/15765,such as 2,4,5,6-tetraaminopyrimidine,4-hydroxy-2,5,6-triaminopyrimidine, 2-hydroxy-4,5,6-triaminopyrimidine,2,4-dihydroxy-5,6-diaminopyrimidine or 2,5,6-triaminopyrimidine, andpyrazolopyrimidine derivatives, such as those mentioned in PatentApplication FR-A-2 750 048, among which may be mentionedpyrazolo[1,5-a]pyrimidine-3,7-diamine,2,5-dimethylpyrazolo[1,5-a]pyrimidine-3,7-diamine,pyrazolo[1,5-a]pyrimidine-3,5-diamine,2,7-dimethylpyrazolo[1,5-a]pyrimidine-3,5-diamine,3-aminopyrazolo[1,5-a]pyrimidin-7-ol,3-aminopyrazolo[1,5-a]pyrimidin-5-ol,2-(3-aminopyrazolo[1,5-a]pyrimidin-7-ylamino)ethanol,2-(7-aminopyrazolo[1,5-a]pyrimidin-3-ylamino)ethanol,2-[(3-aminopyrazolo[1,5-a]pyrimidin-7-yl)(2-hydroxyethyl)amino]ethanol,2-[(7-aminopyrazolo[1,5-a]pyrimidin-3-yl)(2-hydroxyethyl)amino]ethanol,5,6-dimethylpyrazolo[1,5-a]pyrimidine-3,7-diamine,2,6-dimethylpyrazolo[1,5-a]pyrimidine-3,7-diamine,2,5,N7,N7-tetramethylpyrazolo[1,5-a]pyrimidine-3,7-diamine,3-amino-5-methyl-7-(imidazolylpropylamino)pyrazolo[1,5-a]pyrimidine, andtheir addition salts with an acid and their tautomeric forms, when atautomeric equilibrium exists.

[0068] Mention may be made, among pyrazole derivatives, of the compoundsdisclosed in Patents DE 3 843 892 and DE 4 133 957 and PatentApplications WO 94/08969, WO 94/08970, FR-A-2 733 749 and DE 195 43 988,such as 4,5-diamino-1-methylpyrazole,4,5-diamino-1-(β-hydroxyethyl)pyrazole, 3,4-diaminopyrazole,4,5-diamino-1-(4′-chlorobenzyl)pyrazole,4,5-diamino-1,3-dimethylpyrazole, 4,5-diamino-3-methyl-1-phenylpyrazole,4,5-diamino-1-methyl-3-phenylpyrazole,4-amino-1,3-dimethyl-5-hydrazinopyrazole,1-benzyl-4,5-diamino-3-methylpyrazole,4,5-diamino-3-tert-butyl-1-methylpyrazole,4,5-diamino-1-tert-butyl-3-methyl-pyrazole,4,5-diamino-1-(β-hydroxyethyl)-3-methylpyrazole,4,5-diamino-1-ethyl-3-methylpyrazole,4,5-diamino-1-ethyl-3-(4′-methoxyphenyl)pyrazole,4,5-diamino-1-ethyl-3-(hydroxymethyl)pyrazole,4,5-diamino-3-hydroxymethyl-1-methylpyrazole,4,5-diamino-3-hydroxymethyl-1-isopropylpyrazole,4,5-diamino-3-methyl-1-isopropylpyrazole,4-amino-5-(2′-aminoethyl)amino-1,3-dimethylpyrazole,3,4,5-triaminopyrazole, 1-methyl-3,4,5-triaminopyrazole,3,5-diamino-1-methyl-4-(methylamino)pyrazole,3,5-diamino-4-(β-hydroxyethyl)amino-1-methylpyrazole, and their additionsalts with an acid.

[0069] The composition according to the invention can additionallycomprise one or more couplers conventionally used for the conventionaloxidation dyeing of keratinous fibers. Mention may in particular bemade, among these couplers, of meta-phenylenediamines,meta-aminophenols, meta-diphenols, naphthalene couplers and heterocycliccouplers.

[0070] Mention may be made, by way of example, of2-methyl-5-aminophenol, 5-N-(β-hydroxyethyl)amino-2-methylphenol,6-chloro-2-methyl-5-aminophenol, 3-aminophenol, 1,3-dihydroxybenzene,1,3-dihydroxy-2-methylbenzene, 4-chloro-1,3-dihydroxybenzene,2,4-diamino-1-(β-hydroxyethyloxy)benzene,2-amino-4-(β-hydroxyethylamino)-1-methoxybenzene, 1,3-diaminobenzene,1,3-bis(2,4-diaminophenoxy)propane, 3-ureidoaniline,3-ureido-1-dimethylaminobenzene, sesamol,1-(β-hydroxyethylamino)-3,4-methylenedioxybenzene, α-naphthol,2-methyl-1-naphthol, 6-hydroxyindole, 4-hydroxyindole,4-hydroxy-N-methylindole, 2-amino-3-hydroxypyridine,6-hydroxybenzomorpholine, 3,5-diamino-2,6-dimethoxypyridine,1-N-(β-hydroxyethyl)amino-3,4-methylenedioxybenzene,2,6-bis(β-hydroxyethylamino)toluene, and their addition salts with anacid.

[0071] In the composition of the present invention, the coupler orcouplers are generally present in an amount of between 0.001 and 10% byweight approximately of the total weight of the dyeing composition andmore preferably from 0.005 to 6%. The oxidation base or bases arepresent in an amount preferably of between 0.001 and 10% by weightapproximately of the total weight of the dyeing composition and morepreferably from 0.005 to 6%.

[0072] Generally, the addition salts with an acid which can be used inthe context of the dyeing compositions of the invention for theoxidation bases and the couplers are chosen in particular fromhydrochlorides, hydrobromides, sulfates, citrates, succinates,tartrates, lactates, tosylates, benzenesulfonates, phosphates andacetates.

[0073] The dyeing composition in accordance with the invention canadditionally contain direct dyes different from those of formula (I), itbeing possible for these dyes in particular to be chosen from nitro dyesof the benzene series, cationic direct dyes, direct azo dyes and directmethine dyes.

[0074] The medium acceptable for dyeing, also referred to as dyeingsupport, is generally composed of water or of a mixture of water and ofat least one organic solvent, in order to dissolve the compounds whichwould not be sufficiently soluble in water. Mention may be made, asorganic solvent, for example, of lower C₁-C₄ alkanols, such as ethanoland isopropanol; polyols and polyol ethers, such as 2-butoxyethanol,propylene glycol, propylene glycol monomethyl ether, diethylene glycolmonoethyl ether and diethylene glycol monomethyl ether; and aromaticalcohols, such as benzyl alcohol or phenoxyethanol; and their mixtures.

[0075] The solvents can be present in proportions preferably of between1 and 40% by weight approximately with respect to the total weight ofthe dyeing composition and more preferably still between 5 and 30% byweight approximately.

[0076] The dyeing composition in accordance with the invention can alsoinclude various adjuvants conventionally used in hair dyeingcompositions, such as anionic, cationic, nonionic, amphoteric orzwitterionic surface-active agents or their mixtures, anionic, cationic,nonionic, amphoteric or zwitterionic polymers or their mixtures,inorganic or organic thickening agents and in particular anionic,cationic, nonionic and amphoteric associative polymer thickeners,antioxidants, penetration agents, sequestering agents, fragrances,buffers, dispersing agents, conditioning agents, such as, for example,volatile or nonvolatile and modified or unmodified silicones,film-forming agents, ceramides, preservatives or opacifying agents.

[0077] These above adjuvants are generally present in an amount of, foreach of them, between 0.01 and 20% by weight with respect to the weightof the composition.

[0078] Of course, a person skilled in the art will take care to choosethis or these optional additional compounds so that the advantageousproperties intrinsically attached to the dyeing composition inaccordance with the invention are not, or not substantially,detrimentally affected by the envisaged addition or additions.

[0079] The pH of the dyeing composition in accordance with the inventionis generally between 3 and 12 approximately and preferably between 5 and11 approximately. It can be adjusted to the desired value by means ofacidifying or basifying agents commonly used in dyeing keratinous fibersor alternatively using conventional buffer systems.

[0080] Mention may be made, among acidifying agents, by way of example,of inorganic or organic acids, such as hydrochloric acid,orthophosphoric acid, sulfuric acid, carboxylic acids, such as aceticacid, tartaric acid, citric acid or lactic acid, or sulfonic acids.

[0081] Mention may be made, among basifying agents, by way of example,of ammonia, alkaline carbonates, alkanolamines, such as mono-, di- andtriethanolamines, and their derivatives, sodium hydroxide, potassiumhydroxide and the compounds of following formula (III):

[0082] in which W is a propylene residue optionally substituted by ahydroxyl group or a C₁-C₄ alkyl radical and R_(a), R_(b), R_(c) andR_(d), which are identical or different, represent a hydrogen atom or aC₁-C₄ alkyl or C₁-C₄ hydroxyalkyl radical.

[0083] The dyeing composition according to the invention can be providedin various forms, such as in the form of liquids, creams or gels or inany other form appropriate for carrying out dyeing of keratinous fibersand in particular of human hair.

[0084] Another subject matter of the invention is a direct dyeingprocess which comprises the application of a dyeing compositioncomprising a dye of formula (I) as defined above to keratinous fibers.After a leave-in time, the keratinous fibers are rinsed, allowingcolored fibers to appear.

[0085] The application to the fibers of the dyeing compositioncomprising the cationic azo dye of formula (I) can be carried out in thepresence of an oxidizing agent which brings about the bleaching of thefiber. This oxidizing agent can be added to the composition comprisingthe cationic azo dye at the time of use or directly to the keratinousfiber. According to a specific embodiment, the composition comprisingthe cationic azo dye of formula (I) is free of oxidation base and ofcoupler.

[0086] Another subject matter of the invention is an oxidation dyeingprocess which comprises the application to fibers of a dyeingcomposition which comprises a dye of formula (I), at least one oxidationbase and optionally at least one coupler, in the presence of anoxidizing agent.

[0087] The oxidation base, the coupler and the oxidizing agent are asdefined above.

[0088] In the context of permanent oxidation dyeing, it is also possibleto use, as oxidizing agent, enzymes among which may be mentionedperoxidases, 2-electron oxidoreductases, such as uricases, and4-electron oxygenases, such as laccases.

[0089] The color can be developed at acidic, neutral or alkaline pH andthe oxidizing agent can be added to the composition of the inventioneither at the time of use or it can be employed from an oxidizingcomposition comprising it, applied to the fibers simultaneously with orsequentially to the dyeing composition.

[0090] In the case of permanent oxidation dyeing or of direct dyeing,the dyeing composition is mixed, preferably at the time of use, with acomposition comprising, in a medium acceptable for dyeing, at least oneoxidizing agent, this oxidizing agent being present in an amountsufficient to develop a coloring. The mixture obtained is subsequentlyapplied to the keratinous fibers. After a leave-in time of 3 to 50minutes approximately, preferably 5 to 30 minutes approximately, thekeratinous fibers are rinsed, washed with a shampoo, rinsed again andthen dried.

[0091] The oxidizing composition can also include various adjuvantsconventionally used in hair dyeing compositions and as defined above.

[0092] The pH of the oxidizing composition including the oxidizing agentis such that, after mixing with the dyeing composition, the pH of theresulting composition applied to keratinous fibers preferably variesbetween 3 and 12 approximately, and more preferably still between 5 and11. It can be adjusted to the desired value by means of acidifying orbasifying agents commonly used in dyeing keratinous fibers and asdefined above.

[0093] The composition which is finally applied to the keratinous fiberscan be provided in various forms, such as in the form of liquids, creamsor gels or in any other form appropriate for carrying out dyeing ofkeratinous fibers and in particular of human hair.

[0094] Another subject matter of the invention is a multi-compartmentdevice or dyeing ‘kit’ in which a first compartment includes the dyeingcomposition of the invention and a second compartment includes theoxidizing composition. This device can be equipped with a means allowingthe desired mixture to be delivered to the hair, such as the devicesdisclosed in Patent FR 2 586 913 on behalf of the Applicant Company.

[0095] Finally, another subject matter of the invention is thedicationic diazo dyes of formula (I) as defined above. These compoundscan be obtained from the preparation processes described for example inthe documents EP 810824, GB 9619573, RO 106572, J. Chem. Res., Synop.(1998), (10), 648-649, DE 19721619, U.S. Pat. No. 5,852,179, Synth.Commun 1999, 29(13), 2271-2276.

[0096] The following examples serve to illustrate the invention without,however, exhibiting a limiting nature.

EXAMPLES Examples of Synthesis Example No. 1

[0097] Preparation of a Compound of Formula:

[0098] 1.13 g of dimethyl-[4-(pyridin-3-ylazo)phenyl1]amine (0.01 mol),5 ml of dry DMF and 0.61 g (0.0025 mol) of 1,6-dibromohexane are chargedto a fully equipped round-bottomed flask. The mixture is brought for 7hours to 105° C. with stirring. The precipitate is filtered off in thehot state. 0.9 g of a Bordeaux red powder having the following UVabsorption characteristics is obtained: UV (acetonitrile-water 50/50)λ_(max) = 496 nm ε_(max) = 67600 Analyses: Mass ESI+: m/z = 617 [M²⁺ +Br⁻] m/z = 268 [M²⁺/2]

[0099]¹H NMR: (400 MHZ-DMSO) ppm: 1.40 (s-4H); 2.01 (s-4H) CH₂ hexyl3.15 (s-12H)-NCH₃; 4.73 (t-4H)-NCH₂; 6.91 (d-4H); 7.88 (d-4H) phenyl8.33 (dd-2H); 8.76 (d-2H); 9.11 (d-2H); 9.54 (s-2H) pyridine

[0100] A dye giving an intense orange-red color is thus obtained.

[0101] The dimethyl-[4-(pyridin-3-ylazo)phenyl1]amine can be prepared bycoupling the diazonium salt of 3-amino-pyridine with dimethylanilineaccording to the conventional methods for preparing azo compounds oraccording to the teaching of patent DE2509560.

Example No. 2

[0102] Preparation of a Compound of Formula:

[0103] 1st step: 1,6-bis[N-imidazol-2-yl)-4(4-methoxyphenyl)-diazene]:

[0104] 2.02 g (0.01 mol) of(1H-imidazol-2-yl)-(4-methoxy-phenyl)diazene, 50 ml of toluene and 1.21g (0.005 mol) of 1,6-dibromohexane, 1.92 g (0.048 mol) of sodiumhydroxide, (0.0003 mol) of tetrabutylammonium iodide and 2 ml of waterare charged to a fully equipped round-bottomed flask. The mixture isbrought for 20 hours to the reflux temperature, with stirring. Theprecipitate is cooled, filtered off and dried. 0.9 g of an orange-yellowpowder is obtained which is purified by chromatography on silica(eluent: dichloromethane 95/methanol 5). Analyses: Mass ESI+: m/z = 487[M⁺⁻]

[0105]¹H NMR: (400 MHz-DMSO) ppm: 1.27 (s-4H); 1.74 (s-4H) CH₂ hexyl3.85 (s-6H)-OCH₃; 4.33 (t-4H)-NCH₂; 7.16 (d-4H); 7.82 (d-4H) phenyl 7.51(s-2H) imidazole

[0106] The preparation of this type of diamines is described in patentapplication WO 99/37276 and also in the following documents: J. Elgueroet al., Journal of Heterocyclic Chemistry 2-5, 771-782 (1988), Ying-hungSo, Macromolecules 25, 516-520 (1992) and R. G. Xie et al., ChineseChemical Letters 7, 321-324 (1996).

[0107] 2nd Step: Quaternization:

[0108] 0.6 g (0.0012 mol) of the product obtained above, 4 ml ofdichloroethane and 0.47 ml (0.0048 mol) of dimethyl sulfate are chargedto a fully equipped round-bottomed flask. The mixture is brought for 2hours to the ref lux temperature, with stirring. The precipitate iscooled, filtered off and dried. 0.6 g of an orange-yellow powder havingthe following UV absorption characteristics is obtained: UV (ethanol)λ_(max) = 406 nm shoulder at 450 nm ε_(max) = 53400

[0109]¹H NMR: (400 MHz-DMSO) ppm: 1.37 (s-4H); 1.79 (s-4H) CH₂ hexyl3.94 (s-6H)-OCH₃; 4.45 (t-4H)-NCH₂; 4.04 (s-6H-NCH3 7.24 (d-4H); 7.07(d-4H) phenyl 7.96 (d-4H) imidazole

[0110] A dye giving an intense yellow color is thus obtained.

Example No. 3

[0111] Preparation of a Compound of Formula:

[0112] 0.3 g of the product obtained above (0.0004 mol), 2 ml of dry DMFand 0.57 g (0.008 mol) of pyrrolidine are charged to a fully equippedround-bottomed flask. The mixture is brought for 1.5 hours to 100° C.,with stirring. The reaction mixture is poured into 50 ml of ethylacetate. The precipitate is drained and dried. 0.4 g of a Bordeaux redpowder having the following UV absorption characteristics is obtained:UV (ethanol) λ_(max) = 534 nm ε_(max) = 86000

[0113]¹H NMR: (400 MHz-DMSO) ppm: 1.35 (s-4H); 1.77 (s-4H) CH₂ hexyl2.02 (m-8H); 3.44 (unreserved complex HDO+8H) pyrrolidine 4.32(t-4H)-NCH₂; 3.92 (s-6H)-NCH3 6.77 (d-4H); 7.84 (d-4H) phenyl 7.69(d-2H); 7.72 (d-4H) imidazole

[0114] A dye having an intense red color is thus obtained.

Dyeing Examples

[0115] The following dyeing compositions were prepared: Example 4 5 Azodye of example 1 5 × 10⁻⁴ mol — Dye of example 3 — 5 × 10⁻⁴ molPolyethylene glycol 8 EO  12 g  12 g Benzyl alcohol  10 g  10 g Boratebuffer q.s. 100 g 100 g pH 8.9 9.1

[0116] At the time of use, each composition is mixed with an equalweight of 20-volumes hydrogen peroxide (6% by weight).

[0117] Each mixture obtained is applied to locks of gray hair comprising90% permanently waved (BP) or natural (BN) white hair (1 g of lock per10 g of solution). After allowing the mixture to act for 20 min, thelocks are rinsed, washed with a standard shampoo, rinsed again and thendried.

[0118] Each lock is evaluated before and after dyeing in the L*a*b*system, by means of a CM 2002 MINOLTA® spectrophotometer (illuminantD65).

[0119] In the L*a*b* space, the lightness is indicated by the value L*on a scale from 0 to 100 whereas the chromatic coordinates are expressedby a* and b* which indicate two color axes, a* the red-green axis and b*the yellow-blue axis.

[0120] According to this system, the higher the value of L, the lighterand less intense the color. Conversely, the lower the value of L, thedarker or more intense the color.

[0121] The following dyeing results were obtained. Natural hairPermanently waved hair L* a* b* L* a* b* Example 4 23.6 15.8 11.2 22.515.7 10.1 Example 5 21.8 16.7 7.0 20.1 13.9 4.5

1-38. (canceled)
 39. A composition for dyeing keratinous fiberscomprising at least one dicationic diazo dye chosen from those of thefollowing formula (I): W₁—W₂—N═N—W₃—L—W₄—N═N—W₅—W₆ wherein: W₁ and W₆,which may be identical or different, are each chosen from radicals NR₁R₂and OR; W₂ and W₅, which may be identical or different, are each chosenfrom carbonaceous aromatic, pyridine and pyridazinyl groups of formula(II)

W₃ and W₄, which may be identical or different, are each chosen fromheteroaromatic radicals of the following formulae (III) and (IV):

wherein: X₁ is chosen from a nitrogen atom and radicals CR₅; X₂ ischosen from a nitrogen atom and radicals CR₆; Z₁ is chosen from anoxygen atom, a sulfur atom, and radicals NR₈; Z₂ is chosen from anitrogen atom and radicals CR₉; Z₃ is chosen from a nitrogen atom andradicals CR₁₂; Z₄ is chosen from a nitrogen atom and radicals CR₁₃; N¹of the 5-membered ring of formula (III) is connected to the group L andthe bond a of the same 5-membered ring is connected to the azo group offormula (I); the bond b of the 6-membered ring of formula (IV) isconnected to the azo group of formula (I) and N¹ of the 6-membered ringof formula (IV) is connected to the group L; L, R₁, R₂, R₃, R₄, R₅, R₆,R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃, which may be identical or different, areeach chosen from linear and branched C₁-C₁₆ hydrocarbonaceous chains,which can form at least one ring chosen from 3- to 6-memberedcarbonaceous rings, and which can be saturated or unsaturated, whereinat least one carbon atom of the hydrocarbonaceous chains can be replacedby at least one entity chosen from oxygen, nitrogen, and sulfur atomsand an SO₂ group, and the at least one carbon atom of thehydrocarbonaceous chains can be substituted by at least one atom chosenfrom halogen atoms; R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ andR₁₃ can each independently be a hydrogen atom; provided that L, R₁, R₂,R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃ do not comprise a peroxidebond, a diazo radical, or a nitroso radical, and L is a divalentradical; R₈ is chosen from linear and branched C₁-C₈ alkyl radicalsoptionally substituted by at least one radical chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; and from optionally substituted phenylradicals; R₇ with R₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ can form acarbonaceous aromatic ring; R is a radical chosen from C₁-C₃ alkylradicals; and X⁻ is an anion chosen from organic and inorganic anions.40. The composition according to claim 39, wherein the keratinous fibersare human keratinous fibers.
 41. The composition according to claim 40,wherein the human keratinous fibers are hair.
 42. The compositionaccording to claim 39, wherein: R₁ and R₂, which may be identical ordifferent, are each chosen from a hydrogen atom; linear and branchedC₁-C₆ alkyl radicals, optionally substituted by at least one radicalchosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino,C₁-C₂ (di)alkylamino, carboxyl and sulfonic radicals; phenyl radicalsoptionally substituted by at least one entity chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals and from halogen atoms; C₁-C₄alkylsulfonyl radicals; arylsulfonyl radicals; and pyrazolyl,imidazolyl, thiazolyl, oxazolyl, thiadiazolyl, triazolyl, pyrrolyl,pyridyl, pyrimidinyl, triazinyl, pyrazinyl and pyridazinyl radicals; R₁and R₂ may together form a heterocycle chosen from 5-, 6-, 7- and8-membered heterocycles optionally substituted by at least one radicalchosen from a hydroxyl radical; an amino radical; a radical —NR₁₄R₁₅,wherein R₁₄ and R₁₅, which may be identical or different, are eachchosen from a hydrogen atom, linear and branched C₁-C₄ alkyl radicalssubstituted by at least one entity chosen from a halogen atom, and fromhydroxyl, C₁-C₂ alkoxy, amino, C₁-C₂ amino(di)alkyl, and(poly)hydroxyalkylamino radicals; a sulfonylamino radical; a carboxylradical; a carboxamido radical; and C₁-C₆ alkyl radicals optionallysubstituted by at least one radical chosen from hydroxyl and aminoradicals and from a radical —NR₁₄R₁₅; or R₁ and R₂ together form aheteroaromatic radical chosen from 5- and 6-membered heteroaromaticradicals.
 43. The composition according to claim 42, wherein R₁ and R₂,which may be identical or different, are each chosen from a hydrogenatom; linear and branched C₁-C₃ alkyl radicals optionally substituted byat least one radical chosen from hydroxyl, C₁-C₂ alkoxy, amino, C₁-C₂(di)alkylamino, carboxyl and sulfonic radicals; phenyl radicalsoptionally substituted by at least one radical chosen from amino, C₁-C₂(di)alkylamino and (poly)hydroxyalkylamino radicals or R₁ and R₂together form a heterocycle chosen from 5- and 6-membered heterocyclesoptionally substituted by at least one radical chosen from methyl,hydroxyl, amino, (di)methylamino, sulfonylamino, C₂-C₄(poly)hydroxyalkylamino, carboxyl and carboxamido radicals.
 44. Thecomposition according to claim 43, wherein, R₁ and R₂, which may beidentical or different, are each chosen from a hydrogen atom; frommethyl, ethyl, 2-hydroxyethyl, 2-aminoethyl, 1-carboxymethyl,2-carboxyethyl, 2-sulfonylethyl, and 2-methoxyethyl radicals; fromphenyl radicals optionally substituted by at least one radical chosenfrom amino, C₁-C₂ (di)alkylamino and (poly)hydroxyalkylamino radicals orR₁ and R₂ together form a 5- or 6-membered heterocycle chosen frompyrrolidine and piperidine optionally substituted by at least oneradical chosen from methyl, hydroxyl, amino, (di)methylamino, carboxyland carboxamido radicals.
 45. The composition according to claim 44,wherein, R₁ and R₂, which may be identical or different, are each chosenfrom a hydrogen atom; methyl and 2-hydroxyethyl radicals; phenylradicals optionally substituted by at least one radical chosen fromamino, (di)methylamino and (di)(2-hydroxyethyl)amino radicals; R₁ and R₂together form a 5- or 6-membered heterocycle chosen from pyrrolidine,3-hydroxypyrrolidine, piperidine and 3-hydroxypiperidine; or R₁ and R₂together form a 5- or 6-membered heteroaromatic radical chosen frompyrazole, imidazole, pyrrole, triazole, pyridazine and pyrimidine. 46.The composition according to claim 39, wherein R₃, R₄, R₅, R₆, R₁₀, R₁₁,R₁₂ and R₁₃, which may be identical or different, are each chosen from ahydrogen atom; linear and branched C₁-C₄ alkyl radicals optionallysubstituted by at least one radical chosen from hydroxyl, C₁-C₂ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl andsulfonic radicals; phenyl radicals optionally substituted by at leastone entity chosen from halogen atoms and from hydroxyl, C₁-C₂ alkoxy,C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl, andsulfonic radicals; a carboxyl radical; a sulfonylamino radical; asulfonic radical; C₁-C₂ alkoxy radicals; C₂-C₄ (poly)hydroxyalkoxyradicals; an amino radical; C₁-C₂ (di)alkylamino radicals; and C₂-C₄(poly)hydroxyalkylamino radicals.
 47. The composition according to claim46, wherein the halogen atoms are chosen from chlorine, fluorine, andbromine.
 48. The composition according to claim 46, wherein R₃, R₄, R₅,R₆, R₁₀, R₁₁, R₁₂ and R₁₃, which may be identical or different, are eachchosen from a hydrogen atom, C₁-C₄ alkyl radicals optionally substitutedby at least one radical chosen from hydroxyl, amino and C₁-C₂(di)alkylamino radicals; a carboxyl radical; C₁-C₂ alkoxy radicals; anamino radical; C₁-C₂ (di)alkylamino radicals; and C₂-C₄(poly)hydroxyalkylamino radicals.
 49. The composition according to claim48, wherein R₃, R₄, R₅, R₆, R₁₀, R₁₁, R₁₂ and R₁₃, which may beidentical or different, are each chosen from a hydrogen atom, methyl,phenyl and 2-hydroxymethyl radicals, carboxyl, methoxy, ethoxy and2-hydroxyethyloxy radicals, and amino, methylamino, dimethylamino and2-hydroxyethylamino radicals.
 50. The composition according to claim 39,wherein R₇ and R₉, which may be identical or different, are each chosenfrom a hydrogen atom; linear and branched C₁-C₄ alkyl radicals,optionally substituted by at least one radical chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; an optionally substituted phenylradical; a carboxyl radical; and a sulfonylamino radical.
 51. Thecomposition according to claim 50, wherein R₇ and R₉, which may beidentical or different, are each chosen from a hydrogen atom, a phenylradical, C₁-C₄ alkyl radicals optionally substituted by at least oneradical chosen from hydroxyl, amino, C₁-C₂ (di)alkylamino and carboxylradicals.
 52. The composition according to claim 51, wherein R₇ and R₉,which may be identical or different, are each chosen from a hydrogenatom, methyl, phenyl, 2-hydroxymethyl and carboxyl radicals.
 53. Thecomposition according to claim 39, wherein R₈ is chosen from C₁-C₄ alkylradicals optionally substituted by at least one radical chosen fromhydroxyl, C₁-C₂ alkoxy, amino, C₁-C₂ (di)alkylamino, carboxyl andsulfonic radicals.
 54. The composition according to claim 53, wherein R₈is chosen from methyl, ethyl, 2-hydroxyethyl, 1-carboxymethyl,2-carboxyethyl and 2-sulfonylethyl radicals.
 55. The compositionaccording to claim 39, wherein L is chosen from linear and branchedC₁-C₈ alkylene radicals optionally substituted by at least one radicalchosen from hydroxyl, C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino,C₁-C₂ (di)alkylamino, carboxyl and sulfonic radicals.
 56. Thecomposition according to claim 55, wherein L is chosen from linear andbranched C₁-C₈ alkylene radicals.
 57. The composition according to claim39, wherein W₁ and W₆, which may be identical or different, are eachchosen from radical NR₁R₂, wherein R₁ and R₂, which may be identical ordifferent, are each chosen from hydrogen, and alkyl radicals optionallysubstituted by at least one substituent chosen from hydroxyl and aminoradicals.
 58. The composition according to claim 39, wherein W₁ and W₆,which may be identical or different, are each chosen from radical OR,wherein R is a methyl radical.
 59. The composition according to claim39, wherein W₂ and W₅, which may be identical or different, are eachchosen from carbonaceous aromatic radicals.
 60. The compositionaccording to claim 59, wherein W₂ and W₅, which may be identical ordifferent, are each chosen from phenyl radicals optionally substitutedwith at least one radical chosen from alkyl, alkoxy, amino, mono- anddisubstituted amino radicals.
 61. The composition according to claim 60,wherein the phenyl radicals are optionally substituted with at least oneradical chosen from methoxy, methyl, methylamino, and dimethylaminoradicals.
 62. The composition according to claim 39, wherein W₃ and W₄,which may be identical or different, are each chosen from imidazolinium,triazolium, and pyridinium radicals.
 63. The composition according toclaim 39, wherein the at least one dicationic diazo dye of formula (I)is chosen such that W₂ and W₅ are phenylene radicals and W₃ and W₄ areimidazolinium radicals.
 64. The composition according to claim 39,wherein L is chosen from linear and branched C₁-C₈ alkylene radicalsoptionally substituted by at least one radical chosen from hydroxyl,C₁-C₂ alkoxy, amino and C₁-C₂ (di)alkylamino radicals.
 65. Thecomposition according to claim 39, wherein the at least one dicationicdiazo dye of formula (I) is chosen from compounds of the followingformulae:


66. The composition according to claim 39, wherein the at least onedicationic diazo dye of formula (I) is a compound of the followingformula:


67. The composition according to claim 39, further comprising at leastone oxidation base.
 68. The composition according to claim 67, whereinthe at least one oxidation base is chosen from para-phenylenediamines,bisphenylalkylenediamines, para-aminophenols, ortho-aminophenols,heterocyclic bases and the acid addition salts thereof.
 69. Thecomposition according to claim 67, wherein the at least one oxidationbase is present in an amount ranging from 0.001 to 10% by weight,relative to the total weight of the composition.
 70. The compositionaccording to claim 69, wherein the at least one oxidation base ispresent in an amount ranging from 0.005 to 6% by weight, relative to thetotal weight of the composition.
 71. The composition according to claim39, further comprising at least one coupler.
 72. The compositionaccording to claim 71, wherein the at least one coupler is chosen frommeta-phenylenediamines, meta-aminophenols, meta-diphenols, naphthalenecouplers, heterocyclic couplers and the acid addition salts thereof. 73.The composition according to claim 39, further comprising at least oneoxidizing agent.
 74. The composition according to claim 73, wherein theat least one oxidizing agent is hydrogen peroxide.
 75. A process for theoxidation dyeing of keratinous fibers comprising applying, to thefibers, at least one dyeing composition comprising at least onedicationic diazo dye chosen from those of the following formula (I):W₁—W₂—N═N—W₃—L—W₄—N═N—W₅—W₆ wherein: W₁ and W₆, which may be identicalor different, are each chosen from radicals NR₁R₂ and OR; W₂ and W₅,which may be identical or different, are each chosen from carbonaceousaromatic, pyridine and pyridazinyl groups of formula (II)

W₃ and W₄, which may be identical or different, are each chosen fromheteroaromatic radicals of the following formulae (III) and (IV):

wherein: X₁ is chosen from a nitrogen atom and radicals CR₅; X₂ ischosen from a nitrogen atom and radicals CR₆; Z₁ is chosen from anoxygen atom, a sulfur atom, and radicals NR₈; Z₂ is chosen from anitrogen atom and radicals CR₉; Z₃ is chosen from a nitrogen atom andradicals CR₁₂; Z₄ is chosen from a nitrogen atom and radicals CR₁₃; N¹of the 5-membered ring of formula (III) is connected to the group L andthe bond a of the same 5-membered ring is connected to the azo group offormula (I); the bond b of the 6-membered ring of formula (IV) isconnected to the azo group of formula (I) and N¹ of the 6-membered ringof formula (IV) is connected to the group L; L, R₁, R₂, R₃, R₄, R₅, R₆,R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃, which may be identical or different, areeach chosen from linear and branched C₁-C₁₆ hydrocarbonaceous chains,which can form at least one ring chosen from 3- to 6-memberedcarbonaceous rings, and which can be saturated or unsaturated, whereinat least one carbon atom of the hydrocarbonaceous chains can be replacedby at least one entity chosen from oxygen, nitrogen, and sulfur atomsand an SO₂ group, and the at least one carbon atom of thehydrocarbonaceous chains can be substituted by at least one atom chosenfrom halogen atoms; R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ andR₁₃ can each independently be a hydrogen atom; provided that L, R₁, R₂,R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃ do not comprise a peroxidebond, a diazo radical, or a nitroso radical, and L is a divalentradical; R₈ is chosen from linear and branched C₁-C₈ alkyl radicalsoptionally substituted by at least one radical chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; and from optionally substituted phenylradicals; R₇ with R₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ can form acarbonaceous aromatic ring; R is a radical chosen from C₁-C₃ alkylradicals; and X⁻ is an anion chosen from organic and inorganic anions.76. The process according to claim 75, wherein the keratinous fibers arehuman keratinous fibers.
 77. The process according to claim 76, whereinthe human keratinous fibers are hair.
 78. The process according to claim75, wherein the at least one dyeing composition comprises at least oneoxidizing agent.
 79. The process according to claim 78, wherein the atleast one oxidizing agent is mixed at the time of application with theat least one dyeing composition.
 80. The process according to claim 78,wherein the at least one oxidizing agent is applied to the fibers in theform of at least one oxidizing composition simultaneously with orsequentially to the at least one dyeing composition.
 81. A process forthe oxidation dyeing of keratinous fibers comprising applying to thefibers, in the presence of at least one oxidizing agent, at least onedyeing composition comprising, (A) at least one dicationic diazo dyechosen from those of the following formula (I):W₁—W₂—N═N—W₃—L—W₄—N═N—W₅—W₆ wherein: W₁ and W₆, which may be identicalor different, are each chosen from radicals NR₁R₂ and OR; W₂ and W₅,which may be identical or different, are each chosen from carbonaceousaromatic, pyridine and pyridazinyl groups of formula (II)

W₃ and W₄, which may be identical or different, are each chosen fromheteroaromatic radicals of the following formulae (III) and (IV):

wherein: X₁ is chosen from a nitrogen atom and radicals CR₅; X₂ ischosen from a nitrogen atom and radicals CR₆; Z₁ is chosen from anoxygenm, a sulfur atom, and radicals NR₈; Z₂ is chosen from a nitrogenatom and radicals CR₉; Z₃ is chosen from a nitrogen atom and radicalsCR₁₂; Z₄ is chosen from a nitrogen atom and radicals CR₁₃; N¹ of the5-membered ring of formula (III) is connected to the group L and thebond a of the same 5-membered ring is connected to the azo group offormula (I); the bond b of the 6-membered ring of formula (IV) isconnected to the azo group of formula (I) and N¹ of the 6-membered ringof formula (IV) is connected to the group L; L, R₁, R₂, R₃, R₄, R₅, R₆,R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃, which may be identical or different, areeach chosen from linear and branched C₁-C₁₆ hydrocarbonaceous chains,which can form at least one ring chosen from 3- to 6-memberedcarbonaceous rings, and which can be saturated or unsaturated, whereinat least one carbon atom of the hydrocarbonaceous chains can be replacedby at least one entity chosen from oxygen, nitrogen, and sulfur atomsand an SO₂ group, and the at least one carbon atom of thehydrocarbonaceous chains can be substituted by at least one atom chosenfrom halogen atoms; R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ andR₁₃ can each independently be a hydrogen atom; provided that L, R₁, R₂,R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃ do not comprise a peroxidebond, a diazo radical, or a nitroso radical, and L is a divalentradical; R₈ is chosen from linear and branched C₁-C₈ alkyl radicalsoptionally substituted by at least one radical chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; and from optionally substituted phenylradicals; R₇ with R₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ can form acarbonaceous aromatic ring; R is a radical chosen from C₁-C₃ alkylradicals; and X⁻ is an anion chosen from organic and inorganic anions;(B) at least one oxidation base; and (C) optionally at least onecoupler.
 82. The composition according to claim 81, wherein thekeratinous fibers are human keratinous fibers.
 83. The compositionaccording to claim 82, wherein the human keratinous fibers are hair. 84.The process according to claim 81, wherein the at least one oxidizingagent is mixed at the time of application with the at least one dyeingcomposition.
 85. The process according to claim 81, wherein the at leastone oxidizing agent is applied to the fibers in the form of at least onedyeing composition simultaneously with or sequentially to the at leastone dyeing composition.
 86. A multi-compartment dyeing kit, comprising,(A) at least one first compartment comprising at least one dyeingcomposition comprising at least one dicationic diazo dye chosen fromthose of the following formula (I): W₁—W₂—N═N—W₃—L—W₄—N═N—W₅—W₆ wherein:W₁ and W₆, which may be identical or different, are each chosen fromradicals NR₁R₂ and OR; W₂ and W₅, which may be identical or different,are each chosen from carbonaceous aromatic, pyridine and pyridazinylgroups of formula (II)

W₃ and W₄, which may be identical or different, are each chosen fromheteroaromatic radicals of the following formulae (III) and (IV):

wherein: X₁ is chosen from a nitrogen atom and radicals CR₅; X₂ ischosen from a nitrogen atom and radicals CR₆; Z₁ is chosen from anoxygen atom, a sulfur atom, and radicals NR₈; Z₂ is chosen from anitrogen atom and radicals CR₉; Z₃ is chosen from a nitrogen atom andradicals CR₁₂; Z₄ is chosen from a nitrogen atom and radicals CR₁₃; N¹of the 5-membered ring of formula (III) is connected to the group L andthe bond a of the same 5-membered ring is connected to the azo group offormula (I); the bond b of the 6-membered ring of formula (IV) isconnected to the azo group of formula (I) and N¹ of the 6-membered ringof formula (IV) is connected to the group L; L, R₁, R₂, R₃, R₄, R₅, R₆,R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃, which may be identical or different, areeach chosen from linear and branched C₁-C₁₆ hydrocarbonaceous chains,which can form at least one ring chosen from 3- to 6-memberedcarbonaceous rings, and which can be saturated or unsaturated, whereinat least one carbon atom of the hydrocarbonaceous chains can be replacedby at least one entity chosen from oxygen, nitrogen, and sulfur atomsand an SO₂ group, and the at least one carbon atom of thehydrocarbonaceous chains can be substituted by at least one atom chosenfrom halogen atoms R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃can each independently be a hydrogen atom; provided that L, R₁, R₂, R₃,R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃ do not comprise a peroxidebond, a diazo radical, or a nitroso radical, and L is a divalentradical; R₈ is chosen from linear and branched C₁-C₈ alkyl radicalsoptionally substituted by at least one radical chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; and from optionally substituted phenylradicals; R₇ with R₉, R₁₀ with R₁₁, and R₁₂ with R₁₃ can form acarbonaceous aromatic ring; R is a radical chosen from C₁-C₃ alkylradicals; and X⁻ is an anion chosen from organic and inorganic anionsand (B) at least one second compartment comprising at least oneoxidizing composition.
 87. A dicationic diazo compound chosen from thoseof the following formula (I) W₁—W₂—N═N—W₃—L—W₄—N═N—W₅—W₆ wherein: W₁ andW₆, which may be identical or different, are each chosen from radicalsNR₁R₂and OR; W₂ and W₅, which may be identical or different, are eachchosen from carbonaceous aromatic, pyridine and pyridazinyl groups offormula (II)

W₃ and W₄, which may be identical or different, are each chosen fromheteroaromatic radicals of the following formulae (III) and (IV):

wherein: X₁ is chosen from a nitrogen atom and radicals CR₅; X₂ ischosen from a nitrogen atom and radicals CR₆; Z₁ is chosen from anoxygen atom, a sulfur atom, and radicals NR₈; Z₂ is chosen from anitrogen atom and radicals CR₉; Z₃ is chosen from a nitrogen atom andradicals CR₁₂; Z₄ is chosen from a nitrogen atom and radicals CR₁₃; N¹of the 5-membered ring of formula (III) is connected to the group L andthe bond a of the same 5-membered ring is connected to the azo group offormula (I); the bond b of the 6-membered ring of formula (IV) isconnected to the azo group of formula (I) and N¹ of the 6-membered ringof formula (IV) is connected to the group L; L, R₁, R₂, R₃, R₄, R₅, R₆,R₇, R₉, R₁₀, R₁₁, R₁₂ and R₁₃, which may be identical or different, areeach chosen from linear and branched C₁-C₁₆ hydrocarbonaceous chains,which can form at least one ring chosen from 3- to 6-memberedcarbonaceous rings, and which can be saturated or unsaturated, whereinat least one carbon atom of the hydrocarbonaceous chains can be replacedby at least one entity chosen from oxygen, nitrogen, and sulfur atomsand an SO₂ group, and the at least one carbon atom of thehydrocarbonaceous chains can be substituted by at least one atom chosenfrom halogen atoms; R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁₁, R₁₂ andR₁₃ can each independently be a hydrogen atom; provided that L, R₁, R₂,R₃, R₄, R₅, R₆, R₇, R₉, R₁₀, R₁, R₁₂ and R₁₃ do not comprise a peroxidebond, a diazo radical, or a nitroso radical, and L is a divalentradical; R₈ is chosen from linear and branched C₁-C₈ alkyl radicalsoptionally substituted by at least one radical chosen from hydroxyl,C₁-C₂ alkoxy, C₂-C₄ (poly)hydroxyalkoxy, amino, C₁-C₂ (di)alkylamino,carboxyl and sulfonic radicals; and from optionally substituted phenylradicals; R₇ with R₉, R₁₀ with R₁₁ and R₁₂ with R₁₃ can form acarbonaceous aromatic ring; R is a radical chosen from C₁-C₃ alkylradicals; and X⁻ is an anion chosen from organic and inorganic anions,with the proviso that when Z₁ is a sulfur atom, then Z₂ is a nitrogenatom.